<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒子模型</title>
    <link rel="stylesheet" href="./CSS/style.css">
</head>
<body>
<div>
    <form action="index.html" method="post">
        <h1>just one</h1>
    </form>
</div>
</body>
</html>